1. Field of the Invention
The present invention relates to a solenoid valve, and particularly to an improvement in a solenoid valve including a coil assembly accommodated in a solenoid housing made of a magnetic metal and having an end wall at one end thereof, a movable core which is opposed to a stationary core magnetically connected to the end wall and inserted into one end of a center bore and which is inserted into the other end of the center bore, a yoke plate made of a magnetic metal which is opposed to the other end of the coil assembly and coupled to the other end of the solenoid housing, a collar made of a non-magnetic material which is adapted to guide the axial movement of the movable core and inserted into the other end of the center bore through the central portion of the yoke plate, a valve member accommodated in a valve housing connected to the solenoid housing, and a rod operatively connected to the movable core and connected to the valve member.
2. Description of the Related Art
Such a solenoid valve is conventionally well-known, for example, from Japanese Patent Application Laid-open No.3-157576 and the like. In this solenoid valve, one end of the rod is coaxially fitted in the movable core.
However, the conventionally known solenoid valve is of an arrangement such that the movable core and the rod are substantially integral with each other, and moreover the axial movement of only the movable core is guided. For this reason, the position of an axial center of the rod is influenced by the concentricity between the movable core and the rod and the accuracy of the position of the axial center of the collar adapted to guide the movable core. To ensure the smooth axial movements of the movable core and the rod within the collar and the valve housing, the processing accuracy and assembling accuracy of the collar adapted to guide the movable core, the movable core and the rod must be increased, thereby bringing about an increase in cost.
Accordingly, it is an object of the present invention to provide a solenoid valve, wherein the processing and assembling of the collar, the movable core and the rod can be facilitated to provide a reduction in cost.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a solenoid valve comprising a coil assembly including a bobbin made of a synthetic resin and having a center bore, and a coil wound around the bobbin, the coil assembly being accommodated in a solenoid housing made of a magnetic metal and having an end wall at one end thereof; a stationary core magnetically coupled to the end wall and inserted into one end of the center bore; a movable core opposed to the stationary core and inserted into the other end of the center bore; a yoke plate made of a magnetic metal, which has a through-bore in its central portion and which is opposed to the other end of the coil assembly and coupled to the other end of the solenoid housing; a collar made of a non-magnetic material adapted to guide the axial movement of the movable core and inserted into the other end of the center bore through the through-bore; and a valve member which is accommodated in a valve housing connected to the yoke plate and to which a rod operatively connected to the movable core is connected, wherein the valve housing is provided with a guide portion for guiding the axial movement of the rod, and one end of the rod is put into coaxial abutment against the other end of the movable core.
With such arrangement of the first feature, the movable core and the rod are separate from each other and hence, it is unnecessary to increase the processing accuracy for assembling the movable core and the rod to each other, and even if the axial centers of the movable core and the rod are offset slightly from each other, an adverse influence cannot be exerted to the axial movement of the movable core and the rod separately guided by the collar and the guide. Therefore, it is possible to facilitate the processing and assembling of the collar, the movable core and the rod, thereby providing a reduction in cost.
According to a second aspect and feature of the present invention, in addition to the arrangement of the first feature, the valve housing made of a synthetic resin is integrally connected to the bobbin through a plurality of connecting bores provided in the yoke plate. With such arrangement, the bobbin, the yoke plate and the valve housing are integrally connected to one another and hence, the accuracy of the axial centers of the bobbin, the yoke plate and the valve housing can be enhanced easily.
According to a third aspect and feature of the present invention, in addition to the arrangement of the second feature, an outer periphery of the yoke plate integrally coupled by molding between the valve housing and the bobbin is coupled to the solenoid housing on the side opposite from the end wall. With such arrangement, the assembling can be facilitated by integrally coupling the yoke plate upon the formation of the bobbin and the valve housing connected to each other through the connecting bores in the yoke plate.
According to a fourth aspect and feature of the present invention, in addition to the arrangement of the first feature, the collar which has at one end thereof an outward-facing collar portion protruding radially outwards and opposed to an inner surface of the center bore is press-fitted into the through-bore. With such arrangement, the collar is press-fitted into the through-bore using the outward-facing collar portion exerting no influence to the sliding movement of the movable core within the collar. Thus, it is possible to press-fit the collar having a thickness at a small valve to the utmost into the through-bore, whereby the distance between the movable core and the yoke plate can be set at a small value to the utmost to enhance the magnetic characteristic, and the axial movement of the movable core can be guided by the collar fixed to the yoke plate.
According to a fifth aspect and feature of the present invention, in addition to the arrangement of the fourth feature, the collar is provided at the other end thereof with an inward-facing collar portion protruding radially outwards, and one end of the rod through which the inward-facing collar portion is axially movably passed is put into coaxial abutment against the other end of the movable core within the collar. With such arrangement, the other end of the collar is substantially occluded by the rod and hence, it is possible to prevent the entrance of dust into the collar to the utmost.
According to a sixth aspect and feature of the present invention, in addition to the arrangement of the first feature, the yoke plate has a cylindrical portion integrally provided at a center thereof to protrude on the side opposite from the coil assembly and to define a portion of the through-bore. With such arrangement, the collar is supported over an axially relatively long distance by the cylindrical portion integral with the yoke plate and in this manner, the axis of the collar can be prevented to the utmost from being inclined. In addition, it is possible to increase the area of a portion of the yoke plate opposed to an outer surface of the movable core through the collar, and to provide an enhancement in magnetic characteristic by an increase in area of a magnetic path.
According to a seventh aspect and feature of the present invention, in addition to the arrangement of the first or sixth feature, the movable core is integrally provided with a smaller-diameter portion inserted into the collar, and a larger-diameter portion formed to have a diameter larger than that of the smaller-diameter portion and coaxially connected to one end of the smaller-diameter portion at a location outside axially one end of the collar in such a manner that it is opposed to the other end of the stationary core. With such arrangement, despite the insertion of the collar into the center bore in the bobbin, the area of opposition of the movable and stationary cores to each other can be set at a relatively large value, and the magnetic characteristic can be enhanced. Moreover, by cooperation with the increase in area of the magnetic path according to the arrangement of the sixth feature, the magnetic characteristic can be further enhanced.
According to an eighth aspect and feature of the present invention, in addition to the arrangement of the seventh feature, the movable core has a recess coaxially provided at one end thereof, so that a portion of a return spring mounted between the movable and stationary cores is accommodated in the recess. With such arrangement, despite the provision of the larger-diameter portion at one end of the movable core, the movable core can be lightened in weight, and the rapid axial movement of the movable core is possible.
According to a ninth aspect and feature of the present invention, in addition to the arrangement of the seventh feature, the larger-diameter portion has a groove provided in its outer surface to extend over the axially entire length of the larger-diameter portion to define a flow path between the outer surface of the larger-diameter portion and the inner surface of the center bore. With such arrangement, a fluid can be allowed to flow between opposite ends of the larger-diameter portion with the axial movement of the movable core, thereby contributing to the rapid axial movement of the movable core.
According to a tenth aspect and feature of the present invention, in addition to the arrangement of the ninth feature, the movable core has a recess coaxially provided at one end thereof, so that a portion of a return spring mounted between the movable and stationary cores is accommodated in the recess, and a communication bore provided at one end thereof to connect the flow path and the recess to each other. With such arrangement, the movement of the fluid with the axial movement of the movable core can be smoothened, whereby the movable core can be moved more quickly.
According to an eleventh aspect and feature of the present invention, in addition to the arrangement of the first feature, the rod is formed at one end thereof with an abutment face spherical about a phantom center on the axis of the rod, the abutment face abutting against the other end of the movable core. With such arrangement, even if a force from the movable core in a direction offset from the axis thereof is exerted to the rod, an influence cannot be exerted to the axial movement of the rod.
According to a twelfth aspect and feature of the present invention, in addition to the arrangement of the first feature, the bobbin has an accommodating recess provided at one end thereof to open in an opposed relation to the end wall of the solenoid housing, and a spring made of a conductive metal and adapted to exhibit a spring force for biasing the coil assembly toward the yoke plate is mounted between the end wall and an earth plate accommodated in the accommodating recess and leading to the coil. With such arrangement, the earth plate can be electrically connected to the solenoid housing, using the spring for supporting the coil assembly stably within the solenoid housing, whereby the solenoid housing can be grounded. Thus, it is unnecessary to mount a terminal member for the earth plate and hence, the number of parts can be reduced.
According to a thirteenth aspect and feature of the present invention, in addition to the arrangement of the first feature, a connecting shaft portion tightly passed through a through-bore provided in the end wall is integrally connected to the bobbin, and a coupler support plate is integrally formed on a couple made of a synthetic resin to which a terminal member connected to the coil faces, so that the coupler support plate abuts against the outer surface of the end wall, the coupler support plate and the connecting shaft portion inserted through a welding bore provided in the coupler support plate being welded to each other.
With such arrangement of the thirteenth feature, the coupler separate from the coil assembly can be mounted to the outer surface of the end wall of the housing and hence, despite the change in shape of the coupler, it is unnecessary to change the portions excluding the coupler, leading to enhanced general-purpose properties. Moreover, the connecting shaft portion is tightly passed through the through-bore provided in the end wall of the housing and hence, the position of the bobbin, i.e., the coil assembly relative to the solenoid housing within a plane perpendicular to the axis of the solenoid housing can be determined constant. In addition, by the fitting of the terminal member into the coupler, the position of the coupler relative to the coil assembly within the plane perpendicular to the axis of the solenoid housing can be determined constant, and thus, the coupler can be fixed firmly and stably to an outer surface of an end portion of the solenoid housing having a rigidity.
According to a fourteenth aspect and feature of the present invention, in addition to the arrangement of the thirteenth feature, the coupler support plate is formed integrally with the coupler separate from the coil assembly, and the terminal member passed through a terminal-penetration bore provided in the end wall is fitted into the coupler. With such arrangement, the coupler separate from the coil assembly can be mounted to the outer surface of the end wall of the solenoid housing and hence, despite the change in shape of the coupler, it is unnecessary to change the portions excluding the coupler, leading to enhanced general-purpose properties.
According to a fifteenth aspect and feature of the present invention, in addition to the arrangement of the thirteenth or fourteenth feature, at least two sets of the welding bores and the connecting shaft portions are disposed at locations where the coupler is interposed between them. With such arrangement, it is possible to reliably ensure the mounting and fixing of the coupler to the outer surface of the end wall of the solenoid housing.
According to a sixteenth aspect and feature of the present invention, in addition to the arrangement of the thirteenth or fourteenth feature, the coupler support plate is formed into a disk shape. With such arrangement, the load strength of the coupler over the entire periphery of the solenoid housing can be increased.
According to a seventeenth aspect and feature of the present invention, in addition to the arrangement of the thirteenth or fourteenth feature, a protrusion of the connecting shaft portion from the welding bore is pushed and crushed axially and thermally welded to the coupler support plate. With such arrangement, to weld the connecting shaft portion and the coupler support plate to each other, expensive welding equipment and welding jig for a ultrasonic welding and the like are not required, and inexpensive equipment and jig can be employed.
According to an eighteenth aspect and feature of the present invention, in addition to the arrangement of the seventeenth feature, the welding bore is provided, at its end opposite from the end wall, with a tapered portion with its diameter being larger at a location farther from the end wall. With such arrangement, the weld strength in a direction perpendicular to the axial directions of the welding bore can be increased.
According to a nineteenth aspect and feature of the present invention, in addition to the arrangement of the thirteenth feature, a base portion of the terminal member adjacent the bobbin is covered with a covering portion made of a synthetic resin formed integrally with the bobbin and fitted into the terminal-penetration bore. With such arrangement, a guide portion can be utilized for positioning of the bobbin and the coupler relative to the solenoid housing, while providing the insulation between the terminal member and the solenoid housing. Thus, in cooperation with the extension of the connecting shaft portion through the through-bore in the solenoid housing, the positioning of the bobbin and the coupler relative to the solenoid housing can be ensured more firmly.
According to a twentieth aspect and feature of the present invention, in addition to the arrangement of the first feature, the valve housing includes a guide bore coaxially communicating at one end thereof with the through-bore; a partition wall having a first valve bore through which the other end of the rod coaxially disposed in the guide bore is loosely inserted, and a first valve seat, to a central portion of which the first valve bore faces on the side opposite from the guide bore; and a fitting bore which is disposed coaxially with the guide bore with the partition wall disposed between the fitting bore and the other end of the guide bore and which has a step facing on the side opposite from the partition wall; and a valve seat member having a second valve seat at one end and provided at the other end with a limiting collar portion protruding radially outwards is fitted and fixed in the fitting bore in such a manner that a valve chest is provided between the valve seat member and the partition wall and the limiting collar portion abuts against the step. With such arrangement, in a state in which the valve seat member has been fitted and fixed in the valve housing, the second valve seat and the step of the valve housing are disposed at axially displaced locations. Thus, the determination of the position of the second valve seat corresponding to the diversification of the length and the shape of the valve housing can be achieved by only changing the length between the second valve seat and the limiting collar portion, leading to enhanced general-purpose properties.
According to a twenty-first aspect and feature of the present invention, in addition to the arrangement of the twentieth feature, the valve seat member has a second valve bore provided therein over the axially entire length with one end opening into a central portion of the second valve seat, and a filter is disposed to face the other end of the second valve bore with the limiting collar portion of the valve seat member interposed between an outer periphery of the filter and the step, the other end of the valve housing being engaged with the outer periphery of the filter by caulking. With such arrangement, it is possible to facilitate the assembling of the valve seat member and the filter to the valve housing.
According to a twenty-second aspect and feature of the present invention, in addition to the arrangement of the first feature, a valve seat member is fitted and fixed in the valve housing to define a valve chest between the valve seat member and the valve housing, and the spherical valve member is accommodated in the valve chest, so that it can be seated on a valve seat provided on the valve seat member, the valve seat member having the valve seat at one end being provided at the other end thereof with a limiting collar portion protruding radially outwards, the valve housing being provided with a step adapted to abut against the limiting collar portion upon fitting of the valve seat member to define an end of movement of the valve seat member in a fitting direction. With such arrangement, in a state in which the valve seat member has been fitted and fixed in the valve housing, the valve seat and the step of the valve housing are disposed at axially displaced locations. Thus, the determination of the position of the valve seat corresponding to the diversification of the length and the shape of the valve housing can be achieved by only changing the length between the second valve seat and the limiting collar portion, leading to enhanced general-purpose properties.
According to a twenty-third aspect and feature of the present invention, in addition to the arrangement of the twenty-second feature, the valve seat is formed into a tapered shape. With such arrangement, the seatability of the spherical valve member on the valve seat can be enhanced, and a stable seated state of the valve member can be maintained when the valve member is in its closed state.
According to a twenty-fourth aspect and feature of the present invention, in addition to the arrangement of the twenty-second feature, the valve housing is provided with a fitting bore coaxial with an axis of the movable core, and an O-ring is mounted to an outer periphery of the valve seat member fitted in the fitting bore with the limiting collar portion abutting against the annular step formed on an inner surface of the fitting bore, so that the O-ring comes into repulsive contact with the inner surface of the fitting bore. With such arrangement, the valve seat member can be fitted into the valve housing, while maintaining the sealability between the valve chest and the outside.
According to a twenty-fifth aspect and feature of the present invention, in addition to the arrangement of the twenty-second feature, valve member guide members are integrally connected to one end of the valve seat member to come into contact with the valve member at a plurality of points around an axis of the valve seat member to guide the movement of the valve member. With such arrangement, the valve member can be guided with a good accuracy to the valve seat.
According to a twenty-sixth aspect and feature of the present invention, in addition to the arrangement of the twenty-second feature, the valve seat member is formed of a synthetic resin. With such arrangement, it is possible to easily produce the valve seat member, thereby providing a reduction in cost.
According to a twenty-seventh aspect and feature of the present invention, in addition to the arrangement of the twenty-second feature, the valve seat member is formed of a metal. With such arrangement, the accuracy of formation of the valve seat can be enhanced to improve the seatability.
According to a twenty-eighth aspect and feature of the present invention, in addition to the arrangement of the twenty-fourth feature, the valve seat member has a valve bore provided therein over the axially entire length with one end opening into a central portion of the valve seat, and a filter is disposed to face the other end of the valve bore with the limiting collar portion of the valve seat member being interposed between an outer periphery of the filter and the step, the valve housing being engaged with the outer periphery of the filter by caulking. With such arrangement, it is possible to facilitate the assembling of the valve seat member and the filter to the valve housing.
According to a twenty-ninth aspect and feature of the present invention, in addition to the arrangement of the twenty-eighth feature, the filter comprises a net-shaped member supported on an inner periphery of a frame member formed into a ring shape, and the valve bore has a tapered bore portion coaxially provided at the other end thereof with the diameter of its larger-diameter end being larger at a location closer to the filter, while corresponding to the inner diameter of the frame member. With such arrangement, a fluid can be allowed to flow through the substantially entire net-shaped member of the filter, whereby the resistance to the flowing of the fluid can be suppressed.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.